The present invention relates to method and apparatus which creates an image for a display from interlaced ultrasound data, particularly ultrasound data acquired utilizing interlacing techniques including a spot volume method or a sparse volume method.
Ultrasound imaging has always involved a tradeoff between image quality and the image processing resources required to process the image to obtain the results desired by the user. While the rate at which data can be acquired is limited by physics (sound only travels so fast in the human body), the types of image processing that can be performed on the data is limited by the amount and quality of image processing resources that can be brought to bear upon the data. If real time imaging is desired, as it usually is, another limiting factor is the rate of data acquisition.
Ultrasound data is typically acquired in frames, each frame representing a complete sweep of an ultrasound beam across the face of a transducer. In the case of a 1-D transducer, a sweep is typically 2-D pie-shaped. For a 2-D transducer, the sweep can be of a multitude of defined (and undefined for that matter) shape, but for purposes of discussion herein, it will be assumed to be a sweep, originating at the transducer and extending over a 2-dimensional rectangular surface, parallel with the face of the probe, at some distance from the probe. Such a sweep can, for the purposes of discussion, be thought of as being pyramidal in shape.
The amount of ultrasound data produced by a 2-D probe can be difficult to receive and process. It is estimated that to process a relatively large volume (60xc2x0xc3x9760xc2x0) of ultrasound data in real time, a beamformer capable with 16xc3x97 parallelism is required. Such a beamformer would be extraordinarily expensive, especially in a market where the acceptable cost of ultrasound systems is rapidly reducing. The typically solution has been to use a lower cost beamformer with a reduced the frame rate. Thus, there currently exists a tradeoff between the benefit of 3-D ultrasound imaging and image quality due to lack of processing resources.
The present inventors have recognized a need for an ultrasound system that is capable of delivering at least the illusion of a real-time image, thereby increasing the quality of the perceived image, while utilizing standard processing resources, including cost effective beamformers. Further, the present inventors have recognized a need for a 3-D solution that can be added, as an upgrade, to existing 2-D systems.
An ultrasound imaging system that produces a seemingly real-time display by obtaining ultrasound data in an interleaved manner. The system includes a transducer that outputs and receives ultrasonic signals and circuitry that causes the transducer to output the ultrasonic signals in a series of frames in an interleaved manner so as to isonify each of a plurality of portions of a subject matter at different times and forms an image based on the echoes from a plurality of frames.
One example of interleaving is the spot volume method in which the subject matter is divided in to areas, with each area being scanned at different times. A second example of interleaving is the sparse volume method in which the subject matter is scanned with sparse line spacing, e.g. scanning every other line, every second line, every third line, etc. . . . On subsequent scans, the remaining lines are scanned.
An image is constructed using several frames of data, with only the portion actually being scanned being updated with actual data for each display frame. For most imaging tasks, such interleaving will provide an adequate illusion of real-time imaging. If necessary alignment processing or interpolation processing can be used to improve (or at least smooth) image quality.